Are 5th/6th floor walk ups much harder to sell/rent?

I am considering buying a 6th floor walk up in Manhattan. It’s a great area, and the unit is totally redone. The only “downside” I’m grappling with is the 6th floor walk up (12 flights). If I want to rent/sell in the future, and I going to have a tough time, or is the market for people who don’t mind walk ups healthy (given that, and popular neighborhood in Manhattan).